SAN FRANCISCO — The cities of San Francisco and Oakland have joined a class-action lawsuit against former lead-paint and lead-pigment manufacturers following a California court’s rejection of most of the claims made in an earlier suit filed by Santa Clara County. Attorneys representing the two cities also said several other California counties indicated that they also planned to join the suit as plaintiffs, according to press reports.

Attorneys filing the suits said the defendant companies systematically sought to “thwart government regulation and full disclosure of the damage caused by their products,” the San Francisco Chronicle reported. But lawyers representing companies named as defendants said the action by San Francisco and Oakland was not viewed as significant.

Timothy S. Hardy, an attorney representing NL Industries Inc., said the latest suit filed by Santa Clara County differs little from an earlier action that has been largely dismissed by Santa Clara County Superior Court Judge Gregory H. Ward. The judge withheld any ruling on one of nine counts in the suit, and said the plaintiffs could modify their case and refile it. Santa Clara County did so, joined by several other California counties and now, the two Bay Area cities.

“We were quite happy,” Hardy said of the judge’s ruling. “The judge agreed that eight of nine counts should be thrown out.”

According to the Chronicle report, San Francisco City Attorney Louise Renne predicted that the plaintiffs would take a different approach in arguing the case against the defendant companies. She said the plaintiffs would cite a “shared-market” legal theory that she said will allow a court to assign legal and financial responsibility for actions that a company or predecessor organization took years earlier.

But Hardy said he saw little difference in the arguments made in the refiled lawsuit, and he expressed skepticism that the decisions by the cities of San Francisco and Oakland to join the suit would add significant weight to the plaintiffs’ case.

Defense attorneys also pointed out that 50 similar suits filed by other U.S. cities and counties in the last 13 years have been rejected by courts. The Chronicle quoted The Sherwin-Williams Co.’s attorney, Charles Moellenberg, as saying, “If San Francisco and Oakland are planning to jump on board, this is already a sinking ship.”

Defendants in the case include Sherwin-Williams, Atlantic Richfield Co., American Cyanamid Co., DuPont Co., The O’Brien Corp., SCM Chemicals, NL Industries Inc., and the Lead Industries Association, a trade group.